In the news I saw an American politician praying for growing stock market prices. Isn't this considered blasphemy, according to Christian beliefs, like praying to the golden calf?
Praying TO something is different than praying FOR something, so I don't think there is a good way to make a connection to the golden calf issue.
That being said, that seems like a very selfish prayer to make. It is quite possible that such a prayer shows that that money and success (individual or corporate) has become an idol. The example prayer we have to follow in the Lords prayer directs us to pray for just what we need ... our daily bread ... and that God's will be done.
Matthew 6:9–13 (ESV)
Pray then like this:
“Our Father in heaven, hallowed be your name. Your kingdom come, your will be done, on earth as it is in heaven. Give us this day our daily bread, and forgive us our debts, as we also have forgiven our debtors. And lead us not into temptation, but deliver us from evil.